Diisopropylamine → Ethyl 3-tert-butyldimethylsilyloxy-2-cyclopropyloxyimino3-butenoate

Participants

Reaction Conditions

Reaction Steps

To a solution of diisopropylamine (1.32 ml) in tetrahydrofuran (10 ml) was added dropwise 1.55N n-butyl lithium in n-hexane (4.57 ml) at 0° C. The mixture was stirred at 0° C. for 30 minutes. To the mixture was added dropwise a solution of ethyl 2-cyclopropyloxyimino-3-oxobutyrate (syn isomer)(940 mg) in tetrahydrofuran (1 ml) at -60° C. The mixture was stirred at the same temperature for 30 minutes. To the mixture was added tert-butyldimethylsilyl chloride (1.42 g) at -60° C. and the mixture was gently warmed to ambient temperature. After stirred at ambient temperature for an hour, the mixture was poured into saturated aqueous solution of ammonium chloride and extracted with diethyl ether. The extract was washed successively with cold 1N hydrochloric acid, saturated aqueous solution of sodium bicarbonate, saturated aqueous solution of sodium chloride quickly, dried over magnesium sulfate, and concentrated under reduced pressure to give a residue. The residue was subjected to column chromatography on silica gel (15 g) using a mixture of n-hexane and diisopropyl ether (3:1 V/V) as an eluent to give ethyl 3-tert-butyldimethylsilyloxy- 2-cyclopropyloxyimino-3-butenoate (syn isomer)(l.09 g) as an oil.

Provenance & Evidence